Best to get into coil building and get an RTA tank, saves a ton of money is easy to learn and you will never have to put up with crappy manufacturers ripping you off ever again.
I believe they they make stock coils shit on purpose so you have to buy more, I have had same problems with kangertech, aspire, and innoken stock coils, they cost silly money and last a few days if that, then off you go frustrated to buy some more throwing your money down the vaping money pit. This is what made me turn to DIY coil building and juice mixing, I hate these fuckers ripping me off and I won't put up with it.